The present invention relates to a device for positioning a human or an animal lying or sitting on a supporting structure and, specifically, to such a device for selective pelvic elevation and rotation for lateral uterine displacement of an expectant mother during labor and delivery.
proper maternal position during the course of labor and delivery promotes fetal circulation and well being when an expectant mother lies flat on her back in a supine position, she potentially could develop a malady sometimes referred to as supine hypotensive syndrome. That condition arises due to the fact that her blood pressure is lowered when the gravid uterus compresses the thin-walled inferior vena cava, which is the major blood vessel returning blood from her legs to her heart. If compression of the vena cava is sufficient, her heart will be deprived of an adequate supply of blood. As a result, significant hypotension will develop which, in turn, will decrease perfusion in her uterine artery and, hence, to her placental circulation.
Hypotension is most commonly measured in the brachial artery. If such blood deprivation does not cause hypotension to measurably develop in the brachial artery, blood pressure and perfusion to the uterus may still be reduced due to compression of the aorta by the enlarged uterus. Expectant mothers, who receive epidural or spinal anesthesia during labor or delivery, are particularly sensitive to hypotension because their blood pressure is generally depressed by application of the anesthesia.
Common obstetrical practice suggests encouraging an expectant mother in labor to lie on her side in order to remove the compressive effects of the uterus from her inferior vena cava and aorta. If the expectant mother prefers a more supine position, a foam wedge or rolled up towels or blanket are generally placed under one of her hips to avoid development of hypotension and fetal distress. Such a wedge or other device is usually placed under the right hip in order to displace her uterus laterally toward her left side since her easily compressible vena cava lies along the right side of her abdomen.
Since pelvic examinations and vaginal delivery are routinely conducted in a supine position, it may be necessary for the expectant mother to assume a supine or near-supine position at certain times during labor and delivery. Also, while administering an epidural anesthesia, it is essential that the expectant mother not lie on her side due to the fact that her block might otherwise become unilateral.
To further complicate matters, it is not uncommon for an expectant mother to be inadequately anesthetized on one side during the course of labor when utilizing epidural anesthesia. Such anesthetic inequality can sometimes be alleviated by positioning the expectant mother towards the side exhibiting greater pain by appropriately placing a foam wedge under one of her hips. This approach relies on gravity to help promote anesthetic flow toward her lower side and, thereby, to enhance the block in her previously inadequately anesthetized side.
In addition, for a cesarian section, a procedure which currently accounts for a substantial percentage of deliveries, the accepted practice is to initiate the operative incision with the expectant mother's hips tilted laterally by a foam wedge placed under one of her hips. After the baby has been delivered, a medical assistant then removes the wedge so the closing procedure will be mechanically simpler and less awkward. The added activity of removing the wedge, however, constitutes unnecessary intrusion in or near the sterile field and, further, unnecessarily inconveniences the attending surgeon. In addition, repeated use of the same device may lead to the spread of infectious disease, AIDS and the like.
What is needed is a device which can be easily and rapidly used to selectively elevate one of an expectant mother's hip during labor and delivery, such that the expectant mother is rotated into or out of a supine position, without unduly intruding into the sterile field and without interfering with or inconveniencing the attending surgeon or obstetrician.